Origin of our Ideas of Duration, and of the measures of it.
And thus I think it is plain, that from those two fountains of all knowledge before mentioned, viz.

reflection and sensation, we got the ideas of duration, and the measures of it.
For, First, by observing what passes in our minds, how our ideas there in train constantly some vanish and others begin to appear, we come by the idea of SUCCESSION.

Secondly, by observing a distance in the parts of this succession, we get the idea of DURATION.
Thirdly, by sensation observing certain appearances, at certain regular and seeming equidistant periods, we get the ideas of certain LENGTHS or MEASURES OF DURATION, as minutes, hours, days, years, &c.
Fourthly, by being able to repeat those measures of time, or ideas of stated length of duration, in our minds, as often as we will, we can come to imagine DURATION,--WHERE NOTHING DOES REALLY ENDURE OR EXIST; and thus we imagine to-morrow, next year, or seven years hence.
Fifthly, by being able to repeat ideas of any length of time, as of a minute, a year, or an age, as often as we will in our own thoughts, and adding them one to another, without ever coming to the end of such addition, any nearer than we can to the end of number, to which we can always add; we come by the idea of ETERNITY, as the future eternal duration of our souls, as well as the eternity of that infinite Being which must necessarily have always existed.
Sixthly, by considering any part of infinite duration, as set out by periodical measures, we come by the idea of what we call TIME in general..